Patent GB-656088-A (GB)
Title: Improvements in and relating to gas turbine power plant
IPC: F01D5/06
Filed: 1945-06-22
Abstract: 656,088. Gas turbine plant for jet-propulsion; air-compressors. BRITISH THOMSONHOUSTON CO., Ltd. June 22, 1945, No. 16040. Convention date, June 22,1944. [Classes 110(i) and 110(iii)] In a gas turbine plant for jet-propulsion of aircraft the last wheel 14 of the compressor is the only one keyed to the shaft and is of steel. The other wheels 15 are shrunk on the shaft. They may be of aluminium and are secured each to the next by engagement at the rim. For this purpose, connecting rings 25, Fig. 13, have a shrink fit with flanges 23, 24 on the compressor wheels. Emery dust is inserted between the rings and flanges. Each ring is further secured to one wheel by pins 26 and to the other by a caulking 27. To facilitate assembly, the compressor shaft 13 is decreased slightly in diameter in steps as indicated by lines 16. The wheels are held together axially by means of a shoulder 38 and a nut 20 on the shaft and they may be so dimensioned that, when at rest, the aggregate axial length at the rims is greater than that at the centre so that when the assembly is tightened up the outer wheels are oppositely dished. Under running conditions, the centrifugal forces on the dished outer wheels Dress the peripheries of the wheels together. The last wheel 14 is followed by two rings of stator blades 68, 69. The shafts of the axial flow compressor and turbine are supported on three bearings, one at each end of the compressor and one near to the overhung turbine disc. The annular delivery of the compressor is led to a series of circularly arranged combustion chambers having outlets for the heated gases which unite to form an annular admission for the turbine. The rear bearing 65, Fig. 1, of the compressor is carried in the compressor end wall 64 which is integral with the walls of the annular passage 60 and the several branch passages 61, connecting with the combustion chambers. The branches 61 are connected by webs 63 which are integral with an annulus 63a. The structure is reinforced by a tubular part 82 welded to the bearing boss of the end wall 64 and to the annulus 63a, and also by radially disposed webs 66. The whole plant is supported from this structure which carries two trunnions received by supports in the aircraft. The up-stream end of the plant is steadied by a pivoted strut connection with the compressor inlet annulus 30. The turbine bearing 73, Fig. 2, is carried in a ring 74 forming part of a unitary structure comprising a tubular member 81, the up-stream end of which is bolted to the annulus 63a, and radial stiffening webs 83, which are bolted to the webs 63. A dished plate 87 is welded tc the ring 74 and a tubular member 88 to the webs 83 and both are welded to a bolting ring carrying the turbine nozzle support 95. An annular plate 129 also forms part of the structure and it is stiffened by webs 83a. The webs 83, 83a lie between the combustion chambers and the plate 129 is apertured to receive the connections 132 between the combustion chambers and the annular turbine nozzle passage 91. The combustion chambers are connected to the branches 61 as shown in Fig. 6. Tapering flanges 116, 117 on the branches and chambers are clamped together by means of split rings 114. The rings 117 are secured to the walls 105 of the chambers by an annular bellows construction 119 and parts 123, 122 carried by the rings have a sliding fit with the chamber walls. Similar joints 126 connect the chambers with the branches 132 which unite in the nozzle ring 91. The combustion chambers comprise outer tubes 105 which connect with the branches 61 and flame tubes 106 supported within the tubes 105 by spacers 107. The burners 110 are inserted through holes 112 in the branches 61 and are carried by coverplates for the holes. The supporting arm 111 is streamlined and a dummy arm 113 is placed diametrically opposite. Air passes into the flame tubes through holes 134 and some passes by the spacers 107 into the space surrounding the branches 132 and rejoins the main stream by perforations 135. The chamber between the first wheel of the air-compressor and theend wall 31 is closed by labyrinth packings 35, 36 and pressure air from an intermediate stage is conveyed to it, for balancing end thrust, by a pipe 160. Air from an intermediate stage is introduced to a wheel space through orifices 137 and passes to the other wheel spaces by way of grooves 138 in the shaft. Some of this air passes through holes 139 in the last wheel to the down-stream end-chamber and it passes through holes 139a to the space surrounding the tubular member 81. Air is also taken by pipes 155 and delivered to both sides of the turbine disc 70. On the up-stream side, the air is introduced by pipes 154 through the plate 87 and conical baffles 157, 158 direct it on to the turbine disc. On the down stream side the air is introduced at the centre of dished plates 175 and flows past baffles 159 to the periphery of the disc. The bearings are lubricated by oil brought to injectors such as 147 which receive pressure air and blow the atomized oil on to the bearings. The turbine shaft 72 is splined at 77 to the compressor shaft and is supported at a midpoint by a vibration damping bearing 96. The outer race carrier has radial freedom in the diaphragm 99 and is held to it by spring-pressed clamps. The turbine shaft is held axially by a bolt 78 screwed into the compressor shaft nut 20 and the bolt is supported intermediately by enlargements 80. Specifications 515,926 and 593,991, [Group XXVII], are referred to.